Electrical condenser



Dec. 14, 1937. 5 5 CRAMER 2,101,985

ELECTRI CAL CONDENS ER Filed May 9.I 1934 5 Sheets-Sheet l "1 J Aff 7ffm f3 5 Z5@ {wh/7; unlunl'nn 74, 9/ j /n` if@ f7" ff je ZZ- 4 hmmag 5INVENTOR Z55/Ord I l" mer' Dec. 14, 1937. s s CRAMER 2,101,985

ELECTRICAL CONDENSE Dec. 14, 1937. Y s, s CRAMER 2,101,985

ELECTRICAL CONDENSER Filed May 9, 1954 5 Sheets-Sheet 3 INVENTOR 4%.5gg/y ,5f gam/n BY /f I Dec. 14, 1937. s s CRAMER 2,101,985

ELECTRICAL CONDENS ER insu/21 Dec. 14,1937. s. s. CRAMER 'y ELECTRICALcoNDENsER Filed lay 9, 1934 5 Sheets-5118?l 5 INVENTOR ATTORNEY PatentedDec. 14, 193']A PATENT OFFICE z.1o1,9s ELECTRICAL coNDENsEn stanley s.Cramer, Haddon Heights, N. J., as-

signor to Radio Condenser Company, Camden,

Application May 9, 1934, Serial No. 724,688

23 Claims.

This invention relates to improvements in electrical condensers,particularly of the variable type, such as are used in tunable circuitsof radio receiving sets.

Because of the present-day practice of making smaller radio receivingsets, smaller umts, including tuning condensers, must be used in theirconstruction. To reduce the size of the condenser and still havesufcient capacity for the tunable circuits, the plates must be broughtcloser together, which means that greater care must be -used in theassembly of the stator and rotor groups of plates, else the warpingstresses brought about in the manufacturing processes will preventaccurate centering of the stator and rotor plates, and more time mustthen be. spent in getting these plates into accurate alignment.

Such small condensers have thus become precision instruments because thecapacity settings must be stable and the condensers must be capable ofwithstanding the strains and stresses applied to them without affectingthe capacity settings, because present-day practice allows only a smalltolerance in the variations of the capacity of one condenser of a gangwith respect to another. This tolerance is on the order of 1 to 1.5mmfd. While it is customary at the present time to provide the outerplates of a condenser unit so that they may be ilexed at differentpoints to compensate for cer- '30 tain variations in the condensers,including the circuit with which they are connected, the design of thecondenser must be one to give great rigidity. It is one of the objectsof my present invention to produce a condenser which is relatively smalland of light weight as compared with previous designs of the samecapacity, but one which will stand the various abuses without driftingoi the capacity. At the same time, it is a further object to provide aconstruction which can be carried 40 out at an even lower cost..

Another object of my invention is to provide a construction in which theparts are so arranged as to facilitate the accessibility sothat theassembly operations may be quickly and carefully performed.

In the last few years it has been customary, in order to get rigidityand therefore stable capacity, to use an all-metal frame for carryingcondensers, the frame being made from a single piece of metal, usuallyof steel, having shield plates between units either swedged or rivetedin place between the various units of the gang; or, as an alternative,the end plates have been swedged or riveted in place between the sidemembers of the frame in the same manner as the shield plates.

This sort of construction has generally been referred to as the bath tubtype of frame, but such a frame makes the gang condenser of considerableweight. To materially reduce this weight, I have discarded the shell orbath tub type of frame entirely and have made a frame having two rigidmetallic end plates, preferably of steel, held together by very rigidmetallic rods constructed and arranged with Ithe end plates to produce aframe structure having a torsional l0 strength much greater than theframes heretofore used. On certain tests which I have made,

I have found that the frames to be hereinafter described will stand morethan twice the tor-` sional iorce than the ."bath tub type of frame 15previously referred to, with a drifting capacity of the condenser oi'less than 1A of the amount of drift in the condensers mounted in thepreviously described frame.

The advantages of my new construction will 20 appear from thespecification which follows. In the drawingsz.

Figure l is a plan view of a three-gang condenser, only one unit beingillustrated of one form of my invention. 25

Figure 2 is a right-hand end view of Figure 1 with the rotor turnedninety degrees.

Figure 3 is a section on the line 3-3 of Figure 1.

Figure 4 is a section on the line 5 4 of Fig- 30 ure 1. f.

Figure is a view similar to Figure l, but showing a modified form ofmounting the stator element.

Figure 6 is a view on the line 6 5 of Figure 5. 35

Figure '7 is a side elevation of a further modified form of three-gangcondenser showing the rotor turned at an angle of ninety degrees fromits zero or full capacity position. In this form, as well as in Figures1 and 5, no trimmer condenser is illus- 40 trated.

Figure is a View of the right-hand end of the 'gang condenser shown inFigure 7.

Figure 9 is a view looking at one end of the bottom oi one of the statorunits of Figure 7, 45 showing a part of the end plate and one shieldplate.

Figure 10 is -a partial view on the line Iii- I0 of Figure 7.

Figure 11 is a partial view on the line il-ii 50 of Figure 7.

Figure 12 is a sectioncn the line l2-i2 of Figure 7.

`Figure 13 is a side elevation of a three-gang condenser similar to thatshown in Figure 7, but 55 showing certain modified details of mountingthe stators and fastening the end plates in position. v

Figure 14 is a viewl of the right-hand end of Figure 13. I

Figure 15 is a view looking at one end of the bottom of one of thestator units of Figure 13, showing a part of the end plate and oneshield plate.'

Figure 16 is a partial sectional view on the line Figure 17 is a sideelevation of a further form of three-gang condenser similar to thatshown vin Figures 7 and 13, but with certain modified details. r A

Figure 18 is a view of the right-hand end of Figure 17.

Figure 19 is a partial view on the line I9-I9 of Figure 17. Figure 20isa side elevation of a three-gang condenser, only two of the statorunits being illustrated to show certain modied details.

Figure 21 is a partial view looking at the right-hand end of Figure 20.

Figure 22 is a view looking at the bottom of one end of the stator unitsshown in Figure 20, showing details of mounting the stator in the frame.

Figure 23 is a side elevation of the frame of a three-gang condensershowing further modified I which may be used.

` Figure 26 is a fragmentary view of the right.

hand end of the frame shown in Figure 25.

Figure 27 is a fragmentary end view 0 a further modifiedl constructionof the condenser frame.

Figure 28 is a view looking at the bottom of Figure 27.

Figure 29. is an end view, part in sectlonand part in elevation, of astill further modified form of construction.

Figure 30 is a side view of the end of a condenser as constructed inFigure 29.

Figure 31 is a side view of one end of a modifie form of framestructure.

Figure32 is an end view of Figure 31.

Figure 33 is a side view similar to Figure 3l of a condenser frame, butof a modified form'of fastening the bars to the end bearing plates.

Figure 34 is an end view of Figure 33.

Figure 35 is a side View, partly in section, of one end of `a condensershowing a still further modiied form of fastening the bars to the endplates.

Figure 36 is an end view of Figure 35.

Figure 37 is an end view of a still further modiiled form.

Figure 38 is apart sideand part sectional view of Figure 37.

Figure 39 is a part-sectional and part-elevational view of a furthermodication.

Figure 40 is a partial side view of one'end of a condenser showing howthe end` plates may be welded direct to the frame rods.

Referring now to the different views, I and 2 are metallic end plates,preferably of steel and of a thickness to give considerable rigidity.Each of the plates I and 2 is provided with two sets of lugs, one set,3, being provided so that the condenser may be mounted in one angularposition, while the otherl set, 6, is provided so that the condenser maybe mounted in a reverse angular position as will be 'clear by referenceto Figure 2. For holding the end plates land 2 in operative position, Iprovide two similar rods 5 and'6, preferably of steel and of a size torigidly -width of the notch between the forked ends 3 is somewhatsmaller than the diameter of the portion 9 at the base of the grooves 1.Furthermore, the depth of the grooves 1 is suchas to provide aconsiderable radial bearing surface for the lforked ends 8 of the platesI and 2. Thus, when the rods 5 and 6 are forced into position in the endplates I and 2, the plates are securely gripped in position'. The rods 5a'nd 6 have additional annular grooves I to receive the forked ends ofshield plates II, but the depth of these grooves i8 need not be as greatas the depth of the grooves 1, but preferably the shield plates aresecurely gripped `by the rods when they are forced into the positionshown.

The end plate I carries aball bearing race i 2 similar to that shown inmy Patent/1,800,719, for

supporting one end of the rotor shaft I3, the opposite end of which issupportedI in a ball thrust bearing I4 supported by an adjusting screwI5 in the end plate 2. ,While I have indicated this type of bearing inthe end plate 2, it is understood that a bearing similar to that in theend plate I may be used.

The rotor plates I 6 are carried on the shaft I3 in any satisfactorymanner as by grooves within which the plates I6 are staked or otherwiseheld. The stator group of plates I 1 is suspended from the frame rodsand 8 by a saddle I8 having forked ears I9 which tightly fit intoannular grooves 20'in the rods 5 and 6. The projecting tie bar 24, asbest illustrated in Figures 3 and 4.

However, it is to be understood that before the soldering operationtakes place, an assembly tool has been inserted between the stator androtor platesto properly space them an equal distance apart, all in themanner as described and claimed in Cramer application Serial No.717,860, illed March 28, 1934 After the soldering operation iscompleted, the tool is removed, thereby leaving each of the statorsassembled in the frame without any torsional strains thereon. L

As shown in Figures 5 and 6, the stator II of each unit condenser isfastened to the plain rods 5 and 6 in a somewhat diierent. manner fromthat shown in the previous iigures. When the stator plates4 I1 areattached to their tie bars 2li,

"there being one on opposite sides of each stator,

an insulator 2'I is riveted between the tie bars 24 and the shoulderedportion of the plates I1. To the free end' of the insulator 2l, isfastened, as by rivets 28, a metallic support member 29 preferably inthe form of a small steel plate, the opposite end'of which extends intoa longitudinal slot in one of the members and 6, and is staked theretoat 30, thereby giving a suspension type of mounting for the statorsomewhat different from that shown in Figure 1.

In Figures 7 to 12 inclusive, I have illustrated a modied form ofcondenser in which the end plates l and 2 are rectangular in shape butheld together by the frame rods 5 and 6 in a manner similar to thatalready described, except that each of the rods 5 and 6 has alongitudinal groove 3| preferably extending throughout its length, andthe material 32 of the end plates is preferably staked inwardly out ofthe plane of the end plate so as to absolutely prevent the rods 5 and 6from turning. Furthermore, the insulators 33, one on each side of thestator, are positioned in the grooves 3|, being staked in positiontherein as more clearly shown in Figure 1l.

Each of the insulators 33 has a metallic bracket 34 fastened thereto inany satisfactory manner as by rivets 35. The bracket 34 has a pair ofinwardly projectmg arms 36, one on each side of the insulator, and eacharm 36 has a lip 31 extending, one toward the other, as is clearly shownin Figure 9. These lips 31 act as means for assisting in soldering thestator tie bar 24 to the bracket 34. The manner of positioning the rotorplates and stator plates with a special fixture for carrying out thesoldering operation is similar to that already explained with respect toFigure 1. The bracket 34 is provided with a terminal 38 for makingelectrical connection to the stator. Also, it may be noted that eachinsulator 33 may have a tapped hole 39 to receive an adjusting screw foradjusting a trimmer plate which maybe added to each unit in a manner aswill be later referred to on one of the other forms of condensersillustrated such, for example, as shown in Figure 25, wherein thetrimmer plate is fastened to the shield plate It may be noted inFigure^8 that the end plates and 2 may be provided with re-enforcingribs 40 punched either outwardly or inwardly.

In Figures `13 to 16 inclusive, each of the insulators 33 is stakedintogrooves 3| in the rods as in the form shown in Figure 7, and the rods 5being provided in the end bearing plates to assist in the assembly ofthe parts. This means that the studs 50 for supporting the stator, whilesimilar in shape to the studs 4|,. are shorter, thereby making thecondenser of less width than in the form shown in Figures 13 and 14. Inaddition, a somewhat different style of trimmer plate 5| is used, one ofthese trimmer plates being indicated in position in Figure 17, it havinga similar connecting lug 48 as in Figure 13. The trimmer'plate 5| isalso provided with inturned fingers 52 for preventing an insulator notshown but used for separating the plate 5l from the. bar 44, fromturning. Y

In some cases Where the condenser is mounted in whatv might be termed anupside-down position, the fingers 52 act as supports for this trimmervinsulator. Where no trimmer plate is used, a terminal plate 53 isprovided, the same being riveted to the insulator by the end of thestuds In Figure 20, the frame members and 2 are held together in thesame manner; that is, by the rods 5 and 6, as has been described, butthe stator group of plates, only two of which are shown, are fastened toan insulating bar 54 which extends from end to end of the condenserthrough shown, and at the same time, it adds a certain and 6 areattached to the end plates I and 2 inv wherein a pair of studs 4I withshoulders 42 have reduced ends which pass through the insulator 33 andalso through a trimmer plate 43 for riveting the trimmer plate 43securely to the insulator 33. The opposite ends of the studs 4I aresoldered in a manner previously explained to the stator tie bar 24 asclearly indicated in Figure 15.

To provide a cooperative capacity element for the trimmer plates 43, arectangular-shapedbar member 44 is positioned in slots in the bottom ofthe end bearing plates and 2, being staked in position at 45 asindicated. The bar 44 has tapped holes 46 to receive adjusting screwswhich pass through clearance holes 41 in the trimmer amount of stiinessto the Whole frame of the condenser. l

In this form, each of the stators is carried by a bracket 51 fastened tothe bar insulator 54 in any satisfactory manner as by rivets 58, thestator being soldered to the projecting lingers 59 in the mannerexplained in Cramer application, Serial No. 717,860, heretofore referredto. It may be noted that the end plates i and 2 are provided with armsor brackets 66 for mounting the condenser. Similar brackets may beattached to the end bearing plates in certain of the other forms thathave been described.

In Figure 23, the rods 5 and 6 are fastened to the end plates I and 2 ina manner similar to that shown in Figures 18 and 20. A metallic bar 6|.,similar to the bar 55, is staked into position in slots in the endplates I and 2 and in the shield plates but in this case the barinsulator 62 does not pass through the end plates I and 2 but is heldtherebetween to the metal bar 6| as by rivets 63. The stator group ofplates is held to the insulator 62 in the same manner as in Figure 20.

In Figures and 26, bar insulators 64, similar to 54, are used, but thesebars pass through slots in the end plates and 2 and are held in positionas by staking at 65. The stator group 01' plates is held to thevinsulators 64 by brackets plates 43. The screws and insulatingbushings.

used in holes 41 and the trimmer plates are not shown in Figure 13, "buttheir function-is well understood. Each trimmer platehas an ear or lug48 thrown outwardly therefrom for the purpose of making electricalconnection to the stator.

66 which have inwardly projecting fingers somewhat similar to theiingers 59 to which the stator tie bars are soldered. The bracket 66extends downwardly over the insulator so as to act as one In Figures 17,18 and k19, the construction isV very similar to that shown in Figures13 to 16 inclusive, except the frame rods 5 and 6 are moved inwardlytoward the shaft, notches 49 element of a trimmer condenser, the otherelement being a metallic member 61 which may have a bent end folded overand fastened to the shield plate as by rivet 66. An adjusting screw 69and insulator 10, as shown in Figure 25, are used for adjusting theposition of the trimmer plate 61, it being understood that a thininsulator, such as a piece of mica, is mounted between the trim- 0f thevarious forms of condensers utilizing a frame having end plates heldtogether by heavy binding rods, I prefer the construction shown inFigures 17 `to 19 inclusive, where the stator plates are suspended fromthe binding rods and an auxiliary metallic bar is utilized .for anelement of the trimmer condensers, as well as act ing as a stiieningmember for the frame.

In certain of the forms, for example in Figures 7, 13 and l'l, the shafti3 is indicated as being hollow and having a plurality of holes ittherein. These holes are utilized for certain speed-producing mechanismwhich forms no part of my present invention and will therefore not befurther referred to herein.

In Figure 29, the end plates t, only one ofwhich is shown, are fastenedtogether'with rods t in about the same manner as has been previouslydescribed; likewise, the insulators 33 are held to the rod d by stakingthem in the grooves in the rod t. The insulator 33 has holes therein toreceive one or more (2 being shown) insulating bushings l5. Theseinsulators are preferably of isolantite and may be held in theinsulators @t in any satisfactory manner as by a force-nt, the hole inthe insulator 3d or the portion of the bushing l5 tting in this holebeing iirst treated with suitable cement.

The bushing it carries an eyelet ld, the outer ends of which are spunover at 'il to clamp a trimmer plate i8 securely in position. The freeend of the trimmer plate l5 is arranged in overlapping relationship toan upstanding part 'le of the end plates i, an insulator et, preferablyof mica, being used as the dielectric between the parts 19 and thetrimmer plate l, the usual adjusting trimmer screw 69 and insulatingbushing it being used. The stator tie bar 26 is provided with anoutwardly extending lug 8l which may be punched from the tie bar 2d, orit may be made in a separate piece and soldered to the bent portion 2eof the tie bar 24 before the stator Ii is ready to be assembled in thecondenser frame. In either case, after the stator has been placed in theframe the extreme end 82 pf the lug 8i is soldered across the outer faceof the eyelet 16. By this construction, the soldering operation isbrought to the extreme outside portion of the condenser, therebyspeeding up the operation of assembly, it being understood thatVtloetator and rotor elements are positioned by a suitablexture previousto soldering as heretofore ,referred to. In some cases, the insulationpieces 33 may be dispensed with and a piece .of

steel usedin their stead, the isolantite bushing' 15 being suicient toprovide the necessary insulation in mounting the stator. or stators tothe frame. x l

In Figures 31 and 32 the metal of the end plate I is extruded or forcedinwardly at 83 to provide a longer bearing for the rods 6, it beingunderstood that the rods 6 have a force-llt into the end bearing platesi so that the frame produced is a rigid one. I may also spot-weld theange or plate il artiest extruded portion 83 to the rod e, as well asspotweld the end of the rod to the plate around the line 86. Inaddition, the end plates may be provided with another rod e positionedat the bottom of the end plates, this extra rod being fastened to theplates in any of the ways described herein.

In Figure 33, the rod d has a reduced end portion at te force-fittedinto the end plate i, having an extruded portion et the same as inFigure 3l, but in the opposite direction. The reduced end portion et maybe also spot-welded around the distributed flange In Figure 35, the rodt has a reduced end portion de 'which is force-tted into the end de andthe outer portion spun over the plate at di.

In Figures 37 and 38, the end of the rod d may have some other form thancircular, such as a square shape 89, the outer end of the rod being spunover or welded at et.

It is to be understood that any of the previously described forms mayhave a rod at, the bottom of the end plates as shown in Figures Sl to 38inclusive.

In Figure 39, the frame rods, only one oi which, 5, is shown, arerectangular inshape. The frame rods are grooved to receive insulatorsil@ carrying the studs di which are soldered to the tie bars at thepoint 26. Riveted on the outer ends oi the studs lli, against theinsulators is a trimmer plate it which, however, in s case is formedupwardly into the desired shape and es:- tends into capacity positionwith the frame rod d, being adjusted with respect thereto by the screwte, it beingV understood that the usual insuiator is used between thetrimmer plate l@ and the rod 1 In Figure d0, the frame rod d is shown asbeing welded to the end plate 2. The welding open-1 ation may be any ofthe well-known processes, such as spot, butt. or even arc welding,either ot which will securely anchor the bars and end ,dates together,without being obliged to notch or perforate the end plates to receivethe ends This reduced end may be lrnuried at of the frame rods.Therefore, when I speak of l the end plates being securely anchored tothe frame rods, this may be accomplished by any of the ways hereindescribed which are broadly rey ferred to as cooperative formations.

From what has been said, it will be underst that the general object isto get, for a single unit or gang condenser, a frame that is light yetrigid, and one that is easy to make, and at the same time provide aframe that will enable the condenser elements to be mounted thereon asfree from stresses as possible.

What I claim is:

1. An electrical condenser comprising at least one stator and rotor setof elements; a lightweight, high rigidity, non-warping frame forsup-porting said elements in close cooperative vpredetermined and'non-drifting relationship, including rigid metal end bearing plates forsupporting a shaft carrying the rotor plates, means for securely holdingsaid bearing plates in nonwarpingoperative'position including aplurality of metallic rods of a material and size as dened herein anddisposed at least one on each side of the shaft, said rods at theirextremities and the said reduced rod portions. which latter engage mentscomprise gripping surfaces of relatively large lateral area for thepurposes described.

2. An electrical condenser as set forth in claim 1, furthercharacterized in that a plurality of groups of stator Vand rotorelements are provided to form a gang condenser, at least two of saidrods having additional grooves spaced between Said groups of elements,and shield plates tightly tting in said grooves similarly to said endplates.

3. An electrical condenser as set forth in claim 1, furthercharacterized in that said rods have longitudinal grooves at least atleach end, and parts of said bearing plates being forced into saidlongitudinal grooves. A

4. An electrical condenser' as set forth in claim 1, furthercharacterized in that at least two of said rods have longitudinalgrooves extending for at least the major portion of the length thereof,insulators fastened in the grooves of said rods and extending away fromthe rods and having means attached to their opposite ends for supportingthe stator element.

5. An electrical condenser at set forth in claim 1, furthercharacterized in that at least two of said rods have longitudinalgrooves extending from lend toend of the rods, parts of said end platesbeing forced into said grooves, insulators staked in position in saidgrooves and extending away from the rods, and means carried by theinsulators for attaching a stator element thereto.

6. A condenser as set forth in claim 1, characterized in that the statorhaving tie bars is suspended from at least two of said rods by meansincluding insulators fastened to the rods and studs having ends fastenedto the insulators and their opposite ends being soldered to the tiebars.

'7. A condenser as set forth in claim l, characterized in that thestator having tie bars is suspended from at least two of said rods bymeans including insulators fastened to the rods and studs having collarsfitting against one face of the insulator, and ends extending from thecollars and riveted over on the opposite side of the insulator, theopposite ends of the studs being soldered to the stator tie bars.

8. A condenser as set forth in claim 1, characterized in that the statorhaving tie bars is suspended from at least two of said rods by meansincluding insulators fastened to the rods and studs having collarsfitting against one face of the insulator, and ends extending from thecollars and riveted over on the opposite side of the insulator, theopposite endsv of the studs being soldered to the stator tie bars, and a`trimmer condenser plate also rivetedto at least one of the insulatorsby the same stud ends.

9. A condenser as set forth in claim 1, characterized in that the statorhaving tie bars is suspended from a plurality of said rods by meansincluding insulators fastened to the rods and studs having collarsfitting against one face of the insulator, and ends extending from thecollars and riveted over on the opposite sidel of the insulator, theopposite ends of the studs being soldered to the stator tie bars, and atrimmer condenser plate also riveted to at least one of the insulatorsby the same stud ends, said condenser being further characterized inthat metallic bars extend between and are fastened to the end bearingplates, one on each side of the condenser, the bars being positioned toact as one element of the trimmer condenser and as a frame-bracingmember.

10. A condenser as set forth in claim 1, c haracterized in that thestator having tie bars is suspended from a plurality of said rods bymeans including insulators fastened to the rods and parts carried by theinsulators -soldered to the tie bars of the stator, said partscomprising a metal plate fastened to each insulator, each plate havingarms extending beyond the sides of its insulator toward the stator, eacharm having a lip extending one toward the other and being soldered tothe, stator tie bar on each side of the condenser.

11. A condenser as set forth in claim l, characterized in that thestator having tie bars is suspended from a plurality of said rods bymeans including insulators fastened to the rods and parts carried by theinsulators soldered to the tie bars of the stator, said parts comprisinga metal plate fastened to each insulator, each plate having armsextending beyond the sides of its insulator toward the stator, each armhaving a lip extending one toward the other and being soldered to thestator tie bar on each side of the condenser, said metal plate alsoacting as one element of a trimmer condenser.

12. For an electrical gang condenser having a plurality of stator androtor groups of plates, a light-weight, high-rigidity, non-warping frameincluding two rigid, metallic end bearing plates for the shaft carryingthe rotors, said shaft and stators being held in fixed non-warpingspaced relationship by a plurality of metal rods of a material and sizeas defined herein and disposed at least one on each side of the frame,said rods at their extremities and the end plates having cooperativeformations press-fitted together in slidable gripping engagement acrossa portion of the rods reduced in diameter as well as on opposite sidesof said end plates adjacent said reduced rod portions, which latterengagements comprise annular gripping surfaces bounded by the outsidediameter of the rods.

13. A frame for an electrical condenser as set forth in claim 12 furthercharacterized in that the frame has rigid, metallic bar members located,adjacent said rods onV each sidev of the frame and extending between andrigidly fastened to said end bearing plates.

14. A frame for an electrical condenser as set forth in claim l2 furthercharacterized in that the frame has bar members located adjacent saidrods on each side of the frame and extending between and rigidlyfastened to said end bearing plates, said bar members including stripsof rigid metal and insulation, the insulation strip carrying the statorplates.

15. A frame for an electrical condenser as set forth in claim 12 furthercharacterized in that the frame has rigid, metallic bar members locatedadjacent said rods on each side of the frame and extending between andrigidly fastened to said end bearing plates, said bar members carryinginsulation strips that support the stator plates.

16. A frame for an electrical condenser as set forth in claim 12 furthercharacterized in that the frame has bar members located adjacent saidrods and extending between and fastened to said end bearing plates, saidbar members including strips of metal and insulation, the insulationstrip carrying the stator plates, said insulation strip being held inslots in the end bearing plates by the metal strip.

17. A frame for an electrical condenser as set forth in claim 12 furthercharacterized in that the frame has bar members located adjacent saidrods and extending between and fastened to said end bearing plates, saidbar members being a; abonnes of insulating material to which atleast thestator is attached.

18. A frame for an electrical condenser as set 'forth in claim 12further characterized in that to hold said bars therein.

i9. An electrical condenser as set forth in claim l, furthercharacterized in that a plurality of groups of stator and rotor elementsare provided to form a gang condenser, at least two of said rods havingadditional grooves spaced between said groups of elements, and shieldplates tightly fitting in said grooves similarly to said end plates,said rods having further additional annular grooves for receiving statorsupport elements. 1

20. For an electrical condenser having stator and rotor groups ofplates, .a frame including two end bearing plates for the rotor shaftheld in fixed spaced relationship by a plurality of metal rods ofrelatively large diameter disposed at least one on each side of theframe, said rods and end plates having forced/interlocking 'lts made'integral by welding, said rods having relatively large lateral bearingsat least on the inside portions of the end plates.

2l. An electrical condenser as set forth in claim l, furthercharacterized in that at least two of said rods have longitudinalgrooves extendving for at least the major portion of the length thereof,members fastened in said grooves and extending away from the rods. atleast one bushing of insulating material carried by said members, saidbushing having an eyelet going therethrough and a metallic arm fastenedto the eyelet and to a stator element tie bar.

22. An electrical condenser as set forth in claim l, furthercharacterized in that at least two of said rods have longitudinalgrooves extending for at least the major portion of the length thereof,members fastened in said grooves and extending away from the rods; atleast one bushing of insulating material carried by said members, saidbushing having an eyelet going therethrough, a metallic arm fastened tothe eyelet and to a stator element tie bar, further characterized inthat a trimmer plate is fastened to said insulator by said eyelet.

23. For an electrical condenser having stator and rotor groups ofplates, a frame including two end bearing plates for the rotor shaftheld in hxed spaced relationship by a plurality of metal rods disposedat least one on each side of the frame, said rods at their extremitiesand the end i plates having cooperative formations such. that theseparts may be permanently anchored together, further characterized in.that at ieast twoI of said rods have longitudinal grooves therein,insulators fastened in said grooves and en tending away from the rods,at least one rnetal= lic stud carried by each insulator and extending toa point near astator tie bar and soldered thereto, and a trimmer plateheld to said insu lator by said stud and extending into capacityrelationship with said rod, with means carried by the rod for adjustingthe position of the trimmer plate with respect thereto.

